JPS6124799B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray apparatus, such as an X-ray TV bed system, and more particularly to automatic exposure control thereof.

This type of automatic exposure control device is used when a contrast medium such as barium forms a coating within the detection field of a photomultiplier (hereinafter referred to as a "photomultiplier") that detects the output light of an image intensifier (II). The actual detection field area of The brightness of the TV monitor image or the X on the X-ray film at the time of shooting
Some methods have been proposed to prevent variations in the degree of blackening of line images.

Considering the practical aspect of such a system, the area ratio covered by the contrast agent within the actual detection field of the photomal detection section varies greatly depending on the diagnostic purpose, but it is very strict for an automatic exposure control system. In some cases, the coverage can be so high that it can be said that That is,
In the case of such a very high coverage rate, the exposure dose increases abnormally, the brightness of the TV monitor during fluoroscopy becomes extremely bright, and the degree of darkening of the film during imaging also becomes excessive. It becomes blackish. Furthermore, the radiation dose to which the examinee is exposed will also be excessive. Furthermore, in the method described above, the actual detection field area within the detection field is detected by the TV signal and processed as a sensitivity correction signal for the automatic exposure control system. There is a danger that the maximum sensitivity of the automatic exposure control circuit will be exceeded and correction will not be possible. Furthermore, in a system in which detection is performed using a finite area detection field at the center of the image, the fact that the amount of correction exceeds the correction limit value means that the area covered by the contrast agent at the center is extremely large. This also means that the part to be diagnosed is located outside the center of the obtained X-ray image or TV monitor image, and may be caused by poor positioning of the diagnostic part.

The present invention was made based on the above circumstances, and the present invention detects the ratio of the extreme brightness part due to contrast medium coating etc. in the detection field of the detection unit from the video signal for the TV monitor, and performs the detection. In X-ray equipment that corrects the sensitivity of the automatic exposure control system accordingly, it prevents deterioration of image quality due to an abnormal increase in exposure dose and excessive exposure dose to the patient, and substantially improves diagnostic performance. The purpose is to provide an X-ray device that enables

In other words, the present invention is characterized by an Convert to and display on TV monitor
a TV system; a detection means for detecting the amount of light in a predetermined area of the optical system within the TV system; a control means for controlling the amount of X-rays generated by the X-ray source according to the output of the detection means; extracting means for extracting an image signal corresponding to a predetermined detection area of the detection means from the TV image signal; a section detecting means for generating a signal; and a correction signal corresponding to the area ratio occupied by the range corresponding to the signal section to the scheduled detection region based on the output signal of the section detecting means, and the correction signal is controlled by the control section. a protective operation that compares the magnitude of the correction value in the correction means with a set value and displays a warning or stops X-ray exposure by the X-ray source when the correction amount exceeds a predetermined range; It lies in having the means.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an X-ray TV bed system using the present invention. In the figure, 1 is an X-ray tube as an X-ray generation source, 2 is a diaphragm device (including a collimator, etc.) provided at the radiation opening of the X-ray tube 1, 3 is a bed top plate, and 4 is a bed top plate. 3 is a subject placed as a subject, 5 is a spot shot device used for film photography, 6 is an II that converts X-rays into visible light, and 7 is an optical system that guides a visible light image appearing on the output image plane of II6. , 8 is a photodetector provided in the optical system 7, 9 is a TV camera head for capturing the image guided by the optical system 7, 10 is an automatic exposure control circuit that operates based on the output of the photomask 8, 11 is automatic exposure control circuit 1
an X-ray controller, 12, operating based on the output of
A TV camera controller connected to the TV camera head 9; 13 a TV monitor for displaying images obtained by the TV camera head 9 and the TV camera controller 12; 14 a TV monitor for displaying images obtained from the TV camera controller 12; A correction control circuit 15 provides a correction signal and a control signal to the automatic exposure control circuit 10 and the X-ray controller 11, respectively, based on the video signal; This is a high-pressure generator that performs

In detail, the correction control circuit 14 includes, for example, a second
It is configured as shown in the figure. In the same figure, T ₁
~ _T5 are the video signal Vi, the signals H and V corresponding to the horizontal and vertical signal generation sections corresponding to the detection field by the format 8 in the video signal Vi, the integral reset signal _R1 for resetting the integral operation, and the reading operation reset These are the input terminals to which the read reset signal R ₂ is input, and T ₆ and T ₇ are respectively,
This is an input terminal to which a comparison reference level Ec and a correction limit value level Ek are applied. 16 is a comparison circuit that compares the signal level of the video signal Vi obtained by the TV camera controller 12 with a reference level Ec and outputs a predetermined signal in a section exceeding the reference level Ec;
17 is an analog switch that opens and closes the video signal Vi input to the comparator circuit 16; 18 is an analog switch that generates both signals based on the signals H and V corresponding to the horizontal and vertical signal generation sections corresponding to the detection field of the camera 8; 19 is an integration circuit which integrates the output signal of the comparison circuit 16 and is reset by the integration reset signal _R1 ; 20 amplifies the integration output of the integration circuit 19. Amplification circuit, 21 is an amplification circuit 20
Sensitivity correction signal by reading the output peak value (the maximum value up to that point is always read and held)
A pulse height reading circuit 22 which outputs as O ₁ and is reset by a reset signal R ₂ for reading, compares the sensitivity correction signal O _{1 from the pulse height reading circuit 21 with the correction limit level Ek, and compares the sensitivity correction signal O 1} from the pulse height reading circuit 21 with the correction limit level Ek. In this case, a comparison circuit 23 outputs a predetermined signal, and 23 is an output circuit that outputs a protection operation output signal O ₂ for a warning display command or an interlock command to stop exposure in response to the output of the comparison circuit 22. _T8 , _T9
are the sensitivity correction signals from the wave height reading circuit 21, respectively.
O ₁ is an output terminal that outputs the output signal O ₂ from the output circuit 23, and the signals O ₁ and O ₂ output from these output terminals T ₈ and T ₉ are output from the automatic exposure control circuit 10,
are respectively given to the X-ray controller 11.

Next, the operation in such a configuration will be explained.

The outline of this operation is to extract the reduction ratio of the actual detection field due to coating of the contrast medium into the detection field of the photoprint 8 in the automatic exposure control circuit 10 from the video signal Vi for the TV monitor, and to output the output to the automatic exposure control system. When processing for sensitivity correction, if the correction amount exceeds the maximum sensitivity of the automatic exposure control system, that is, if the coverage rate of contrast agent etc. becomes high and the actual detection field becomes extremely narrow, In the sense that there is a risk that the function of the automatic exposure control system may become disabled, a warning is displayed using a display such as an indicator light, or an X-ray interlock is activated to prevent danger during photographing.

First, during fluoroscopy, a video signal Vi is extracted from the TV camera controller 12 and processed by the correction control circuit 14. The video signal Vi input to the correction control circuit 14 is applied to the detection field of the photo frame 8, that is, the third
Horizontal and vertical period signals corresponding to S ₀ shown in Figures a and b [Vi shown in Figure 4 a, for example, S ₁ i to S ₁ j intervals of Hi to Hj, further organized, 1 shown in Figure 4 b Only the video signal Vi interval S ₀ in the frame is extracted by the analog switch 17 and applied to the next-stage comparison circuit 16 [signal A in FIG. 4c]. This signal A is compared with a comparison reference level Ec in the comparator circuit 16, and when it exceeds this level, the comparator circuit 16 outputs a pulse width signal B of a constant level height ("1" level).
As shown in Figures 4d and 5d, this signal B has a pulse width corresponding to the actual detection field _S1 (portion not covered with contrast agent, etc.) within the detection field _S0 of the photoprint 8. It's a signal. Therefore, the comparison reference level Ec is the lower limit of the video signal Vi that can be considered to be in the X-ray transmission range.
It is at a level equivalent to Vimin. Signal B when the entire detection field S ₀ functions as the real detection field S ₁ (S ₀ = S ₁ )
(pulse width C ₀ ) is the final output O ₁ and the reference value Vno (1V
or a value such as 10V) is processed by an integrating circuit 19, an amplifier circuit 20, and a wave height reading circuit 21 that are set in advance. As shown in Figure 3b and Figures 5a to 5e, the percentage of decrease in the actual detection field _S1 is due to the fact that the entire detection field _S0 is covered with opaque substances such as contrast agents and lime adhesion. It is output as Vn ₁ at output O ₁ . If this level Vn ₁ is set to Vn ₀ as the reference value (for example, 1V), then the output value of Vn ₁ = 0.3 is that the actual detection field S ₁ is 30%.
This means that the value has decreased. Therefore, if correction is made to increase the sensitivity of the control system to account for the decrease in the actual detection field _S1 , the sensitivity of the entire system will be constant and stable automatic exposure control will be possible.

Therefore, the output O ₁ corresponding to the actual detection field S ₁ is
When set to 0.3, the sensitivity correction ratio to the control system is the reciprocal of
It becomes 3.33 times. The correction ratio of this control system becomes higher as the level of output O ₁ decreases. When the level of the output O ₁ decreases, the actual detection field S ₁ of the detector becomes narrower, and the amount of detected signal decreases in proportion to this, and the S/N of the entire control system including all of these decreases. This increases the risk of malfunction. Moreover,
In an extreme state, that is, when the output _O1 becomes zero, the function of the automatic exposure control system becomes completely disabled. Therefore, as a matter of course, the correction ability of the system as a whole is limited. This correction limit value Vnmin is set in advance as Ek, and the comparison circuit 22 compares the output O ₁ with the set level Ek. If the output O ₁ becomes less than Ek, the output circuit 23 of the next stage outputs an alarm signal. A display drive command for this purpose or an interlock circuit drive command for stopping X-ray exposure (at least one of these) is processed to the X-ray controller ₁₁ as an output signal O2.

As described above, according to the present invention, an X-ray source that generates X-rays and an X-ray image of a subject based on X-ray exposure by this X-ray source are converted into an optical image.
A TV that converts to TV image signals and displays them on a TV monitor.
a detection means for detecting the amount of light in a predetermined area of the optical system within the TV system; a control means for controlling the amount of X-rays generated by the X-ray source according to the output of the detection means; and a TV of the TV system. extracting means for extracting an image signal corresponding to a predetermined detection area of the detecting means from the image signal; and a signal corresponding to a signal section of a predetermined level range in the image signal based on the image signal extracted by the extracting means. generates a section detecting means, and based on the output signal of the section detecting means, generates a correction signal according to the area ratio occupied by the range corresponding to the signal section with respect to the scheduled detection area, and supplies the correction signal to the control means. A correction means, and a protective operation means that compares the magnitude of the correction value in the correction means with a set value and displays a warning or stops X-ray exposure by the X-ray source when the correction amount exceeds a predetermined range. As a result, the proportion of extreme brightness due to coating of contrast agent in the detection field of the detection unit using photographic images, etc. is detected from the video signal for the TV monitor, and the sensitivity of the automatic exposure control system is corrected according to the detection. In the X-ray apparatus, it is possible to prevent deterioration of image quality due to an abnormal increase in exposure dose and excessive exposure dose of the subject, and it is possible to provide an X-ray apparatus that can substantially improve diagnostic performance.

It goes without saying that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams showing the configuration of an embodiment of the present invention, and Figures 3a and 3b show the relationship between the detection field and the coating with contrast agent, etc., to explain the operation of the embodiment. Figures 4 a-e and 5 a-
e is a waveform diagram of each part for explaining the operation of the same embodiment. 1... X-ray tube, 2... Diaphragm device, 3... Bed top plate, 4... Subject, 5... Spotshot device, 6... II, 7... Optical system, 8... Photo multiplier (Photography), 9...TV camera head, 10...Automatic exposure control circuit, 11...X-ray controller, 12...TV camera controller, 13...TV monitor, 14...Correction control circuit, 15... High voltage generator, 16... Comparison circuit, 17... Analog switch, 18... Measurement section detection circuit, 19... Integrating circuit, 20... Amplifying circuit, 21... Wave height reading circuit,
22... Comparison circuit, 23... Output circuit.

Claims (1)

[Claims] 1. An X-ray source that generates X-rays, converting an X-ray image of a subject based on X-ray exposure by this X-ray source into an optical image, converting the optical image into a television image signal, and displaying it on a television monitor. TV series and
a detection means for detecting the amount of light in a predetermined area of the optical image in the television system; a control means for controlling the amount of X-rays generated by the X-ray source according to the output of the detection means; extracting means for extracting an image signal corresponding to a predetermined detection area of the detecting means from the image signal; generates a section detecting means, and based on the output signal of the section detecting means, generates a correction signal according to the area ratio occupied by the range corresponding to the signal section with respect to the scheduled detection area, and supplies the correction signal to the control means. a correction means, and a protective operation means that compares the magnitude of the correction value in the correction means with a set value and displays a warning or stops the X-ray exposure by the X-ray source when the correction amount exceeds a predetermined range. X-ray equipment.